Why aren’t policymakers stepping in to help protect our kids? In part because food and media companies are successfully using the First Amendment as a shield.

But new research paves the way for government to take action to protect children from junk food marketing, building a strong case to establish that much of this advertising falls outside the scope of First Amendment protection.

The controversy over whether government has the right to regulate food marketing to kids came to a head last summer, after a group of federal agencies proposed a set of voluntary recommendations suggesting how food companies could market to kids more responsibly. Food, entertainment and advertising lobbyists launched a massive campaign to derail the recommendations, arguing that the First Amendment protects industry from any government action involving food marketing to children.

A coalition of legal scholars stepped in to point out that because companies would be free to ignore the recommendations, no one’s First Amendment rights were at stake. Still, industry has succeeded in stalling, if not quashing, the proposed guidelines.

For the first 200 years of our country’s history, the First Amendment had nothing to do with advertising. It wasn’t until about 35 years ago that the Supreme Court expanded the concept of free speech to apply to advertising, recognizing that the unimpeded flow of commercial information is important for our market economy.

But the court made it clear that false and “inherently misleading” advertising does not qualify for First Amendment protection. In two research articles published this month, I joined with leading scientists on this issue to line the evidence up against the law.

A substantial body of research on children’s cognitive development shows that any advertising targeted at children under 12 is by definition inherently misleading. In an article released Feb. 8 in “Health Affairs,” I joined colleagues to look at the three levels of understanding it takes to comprehend advertising: distinguishing advertising from other media content; recognizing the selling intent of advertising messages and recognizing that the selling intent leads to inherent bias in advertising.&nbsp; Children generally don’t master all three levels of understanding until they’re 11 or 12 years old because, even if they can identify an ad and its selling intent, they don’t have the critical thinking capacity to grasp the embellishment in marketing messages.

There is no plausible way to advertise to a young child without being misleading. So the government should be able to set limits on all advertising directed primarily at children under 12 — or, if it chooses, to restrict a subcategory (such as junk food advertising) that is particularly harmful to children — without violating the First Amendment.&nbsp;

Food marketing to adolescents raises similar concerns. For an article in this month’s issue of the “American Journal of Public Health,” my co-author and I show how food marketers exploit many of the vulnerabilities inherent in adolescence. Marketers now frequently disguise promotions as video games and other entertainment; track young people online and through cell phones; follow conversations on Facebook and Twitter; and collect personal data to tempt youth with junk food promotions.

Psychological research consistently shows that adolescents are much more vulnerable than adults to advertising messages because the part of the brain that directs impulse control and maturity of judgment does not fully develop until adulthood. And these high-tech marketing tactics are specifically designed to trigger subconscious, emotional behavior such as mindless snacking and the surrender of personal data.&nbsp;

To be sure, parents bear responsibility for teaching their kids healthy habits. But what parent, no matter how well-intentioned, can compete with aggressive and sophisticated multimillion-dollar marketing campaigns? Kids are bombarded all day long with ads countering the messages their parents try to impart.

And while food companies have pledged — with great fanfare — to scale back unhealthy food marketing to kids, studies show these efforts have been woefully inadequate. For instance, on Nickelodeon, the most popular children’s TV station, ads for foods of poor nutritional quality went down from about nine in 10 of all food ads (in 2005, before self-regulation) to eight in 10 (in 2009, after the self-regulation initiative was implemented).

Federal policymakers are legally free to pursue a range of strategies to help protect children and teens from dangerously deceptive marketing, as long as the regulations are tailored to the appropriate age group. They could bar online junk food “advergames” aimed at children and teens. They could cap the number of junk food ads on children’s TV. They could limit the use of product placement in programming and licensed characters in ads directed to children.

It’s only politics, not law, that’s standing in the way.

Samantha Graff is director of legal research at Public Health Law &amp; Policy.